Family of drugs widely used to treat arterial hypertension and angina, as well as for local treatment of glaucoma.
- Beta-blockers and asthma
- Beta-blockers and anaphylactic shock
- Beta-blockers and local allergic effect
One 40 or 80 mg tablet of propranolol can induce bronchoconstriction in 50% of asthmatics, but the rate is probably much lower with cardioselective beta-blockers.
Bronchoconstriction also occasionally occurs in patients with chronic bronchitis. 13 deaths and 200 major reactions to timolol maleate eye drops have been reported in asthmatics in the USA.
Beta-blockers and anaphylactic shock: unknown.
Beta-blockers in eye-drops are widely used for the treatment of glaucoma; the local allergic effect has recently been recognized.
Asthma, bronchospasm, dyspnea, apnea in children, respiratory arrest.
Anaphylactic shock to beta-blockers is characterized by bradycardia, despite collapse and poor response to epinephrine.
Eczema of the eyelids, contact conjunctivitis with beta-blockers containing eye-drops.
Beta-blockers and asthma: clinical signs and spirometric data.
Beta-blockers and anaphylactic shock: clinical signs.
Beta-blockers and eczema: patch-tests 0.5% aq. or pure eye-drops.
The mechanism underlying the ability of beta-blockers to produce bronchoconstriction remains unclear.
Beta-blockers and anaphylactic shock: beta-blockers inhibits the production of cyclic AMP (by reducing intracellular levels) and lower the threshold of mediator release by mastocytes and basophils. Beta-blockers decrease endogenous adrenaline secretion by blocking beta-2-receptors at synapses, and inhibit beta 1 effects of exogenous and endogenous adrenaline on the heart.
In contact allergy, beta-blockers have a very close structure; most of them cross-react. This may be due to a common aldehyde after primary metabolism.
Beta-blockers and asthma:
- If a beta-blocker must be administered to an asthmatic pa tient, use a selective beta 1 agent, if necessary determined by quantitative measurement of cardioselectivity:
Clinical surveillance and spirometry at the time of administration.
Administration in hospital:
Day 1: 1/10th of the dose.
Day 2: 1/5th of the dose.
Day 3: 1/2 of the dose.
Day 4: full dose.
- If beta-blocker eye drops must be administered to an asthmatic patient, first test tolerance, e.g. to timolol: instillation of one drop of timolol collyre at 0.50% in each eye followed by second instillation 20 minutes later; clinical surveillance (chest auscultation, pulse and arterial blood pressure) at start then at 15, 30, 60 and 120 minutes; perform spirometry at the same time.
- The best agent available at the present time is a beta 1 selective product: betaxolol.
Beta-blockers and anaphylactic shock:
- refractory to adrenaline;
- use of isoprenaline, dopamine, or glucagon;
- need for blood volume expansion (6 to 7 l).
- Skin-test and desensitization under beta-blockers is prohibited.
- For anesthesia, either discontinue beta-blockers 48 hours before surgery, or perform an isoprenalin test during surgery (seldom done).
Beta-blockers and contact eczema with eye-drops:
Avoidance. The risk of recurrence is high if another local beta-blocker is used.